WhiteHot

iTrader: (1)

I just finished up my LT1 build. Had the block assembled by the machine shop --> Manley .020 over forged pistons, Eagle 6" rods, stock crank, ARP main studs, cc306 cam. I've got TPiS/AFR 187 cc heads with Proform 1.6 rr, Trickflow 7.2" pushrods and new GM Performance parts lifters. Also did a double roller chain with Meziere water pump. It's a 95 engine if that matters.

The car idled open headers for probably 10 minutes and then I changed the oil and threw the exhaust on it. Upon start up after hooking up exhaust, I get this noise. I have no idea what this could be.

RamAir95TA

iTrader: (2)

The velocity and tone of the knocking would lead me to believe it's something in the valvetrain. Perhaps a rocker hitting the valve cover?

WhiteHot

iTrader: (1)

I know, it doesn't sound right to be a bottom end knock. I pulled the valve covers off and saw no marks on them or the rockers. Could too much preload on the rockers cause this sound? What about timing chain making contact with the cover?
Piston slap?

RamAir95TA

iTrader: (2)

A mechanics stethoscope (or a piece of hose) would prove to be invaluable in this situation. A noise of that volume should be pretty easy to track down. If something were hitting the valve covers I would assume you'd be able to feel it with your hand.

What timing set are you running? If the rockers were too tight the valves would hang open and it would run poorly.

WhiteHot

iTrader: (1)

Cloyes 9-1145

RamAir95TA

iTrader: (2)

Did you check your timing cover for clearance? Most LT1 timing covers will not accept a double roller without some sort of grinding. What year timing cover are you using?

old93camaro

iTrader: (8)

lol you keep running it it may stop after it grind what every its hitting away. but it sounds like its hitting the value covers, take both off and then run it and see if you get that noise

WhiteHot

iTrader: (1)

It's definitely not hitting the valve covers, already ran it with them off. It was coming from deeper down, sounded like the middle front. Tore it down to the timing chain and found wear marks on the timing cover. It's a 95 cover. I heard about it making contact but didn't feel anything while spinning it by hand so I thought I was good to go. I didn't think something like that would make that much noise.

There is no way I would ever just let it run and clearance itself. I just finished up with a rebuild and there was metal in EVERYTHING from bad mains and I'm not dealing with that again.

WS Sick

It's gnomes with hammers....,
I hate to say it but it sounds like piston kissing head to me.

Matts94Z28

iTrader: (6)

WALK CRANK WALK!! Oh wait...


Did you clearance the timing cover for the double roller? If not you will get a similar sound and it will look like this. Ask me how I know.

the jester 812

iTrader: (5)

^^^ mines a gen3 engine but i know that double timing can cause alot of issues, i had to have my oilpump shimmed and a few other things.

robsquikz28

iTrader: (246)

Thats the exact same thing I thought immediately when I heard the noise. You need to pull the valve cover and see if its hitting. Did you clearence those new valve covers for promags or not?

robsquikz28

iTrader: (246)

check the timing cover too and see if theres any wear marks.

WhiteHot

iTrader: (1)

It's not coming from the valve covers, I know that for sure. They were tapping a tad, I already clearanced those. I took the timing cover off and don't see any marks at all. I would imagine even after running for 20 minutes it would show signs. I think I got something else going on here.

razor02097

Did the engine have any over travel from the piston stroke?
If so what size head gasket are you using to compensate?
Did you degree the cam or how did you set the valve timing up?

WhiteHot

iTrader: (1)

Nope, they were flat tops and didn't extend past the bore, they were pretty much flush with it. I didn't degree the cam, just set it to factory spec with the timing marks on the gears.

fergymoto

iTrader: (129)

It's too fast to be valvetrain and I would even say too fast to be the piston making contact with something. I would look for the crank to be hitting something or a problem in the timing set area. Are you sure it's nothing in the clutch/flywheel area too?

SS RRR

iTrader: (2)

I'd suggest checking the clutch/flywheel assembly.

old93camaro

iTrader: (8)

if not how close was the windage tray to the crank when you put the oil pan on sounds like it may be hitting that really sounds like a deeper in the oil pan

WhiteHot

iTrader: (1)

It's the stock, original crank and windage tray that I took out of the engine, the crank was ground and oversized bearings were used. There was clearance just like a stock engine. Only other thing I can think of is the rods touching the pan, but once again, stock crank. I'm gonna try clearancing the timing cover and put it back together. If it still does it I'll pull the pan and see if I can find anything. I'm trying to avoid pulling the pan as its not easy to do in this car at all.